Many industries today produce products which require packaging. This is especially true in industries such as the powdered soap detergent manufacturing industry where the product produced would be rather hard to sell without being packaged. With the packaging being such an integral part of selling the product, industrial packaging operations have evolved in order to better package products and to handle packaging on a mass-production scale. The industrial packaging operations which have evolved, however, have not been perfected and are plagued with problems due to 1) product proliferation and diversification which requires quickly changeable equipment to handle a myriad of different package sizes and 2) the need to ever more efficiently and cost effectively containerize the product in order to remain competitive.
Folded cartons have emerged as one of the most efficient ways to package certain products. Carton folding apparatus has developed which uses a combination of folding rails, compression fingers and transport rails to fold, close and seal the flaps of scored cartons in order to containerize a product. The folding rails, compression fingers and transport rails are positioned within a flap closure station so that the folding rails fold the glued flaps of the cartons, the compression fingers compress the cartons to spread the glue and the transport rails provide a smooth, non-abrasive surface along which the carton can slide to further spread the glue while at the same time allowing the glue to dry so that the carton may set. Unfortunately, conventional folding rails, compression fingers and transport rails do not always function as designed and numerous problems have become associated with carton folding operations.
A major problem associated with conventional carton folding apparatus is that the folding rails do not consistently square the cartons. Folding rails are old and well known in the art and come in a variety of shapes and sizes. However, current carton folding operations generally include folding rails that are bent from metal bars or strips in order to have a vertical section, a horizontal section and a transitional section between the vertical and horizontal section. The folding rails bent from metal bars or strips do not consistently fold and square cartons because the transitional sections of the folding rails are not bent to any particular or predetermined curvature, but rather to whatever curvature is attained in arriving at the vertical and horizontal sections.
Thus, folding rails that are bent from metal bars or strips often introduce too much stress into the folding process to cause a skewing of the cartons. Stated another way, when a carton having major and minor flaps is conveyed through a conventional carton folding operation using folding rails bent from metal bars or strips to fold and close the cartons, the folding rails do not consistently fold the flaps so that the cartons are in true square. With many industries today having quality control standards that require cartons out of true square by more than 1/32 of an inch to be rejected, often over 5% of folded cartons fail to meet industry standards. This makes it hard for industry to meet its production quotas and results in waste of both finished cartons and time and money spent on costly, time-consuming trial and error attempts to rebend the transitional sections of the folding rails to a curvature producing acceptably squared cartons.
Another problem associated with conventional folding rails is the lack of adjustability and interchangeability between rail sizes for folding cartons of varying sizes. Conventional folding rails are designed in a sort of one size fits all mentality to fold a limited range of carton sizes and to fold either full-size flaps or shied flaps, i.e., inner and outer major flaps of a carton that are not the full size of the carton opening and thus do not fully overlap each other. Thus, excessive down time is created when the folding rails need to be changed to folding rails of another size to accommodate folding cartons in other size ranges or to accommodate folding shied flaps. Indeed, it often takes a skilled technician as much as 8 to 12 hours to reposition or change-over the heavy stainless steel rails currently used in conventional carton folding apparatus in order to fold cartons of a different size. During the down time, the plant is not in operation and money is being lost.
Conventional folding rails also suffer from problems of incorrect feeding and jamming of the cartons at the folding rail. If a carton is fed incorrectly through a conventional carton folding apparatus, whether because of hot glue build-up on a carton flap, incorrect height of the transport rails or otherwise, a jam at the folding rail will occur and the folding rails will become deformed. A mechanic is then usually required to spend numerous hours, sometimes days, of trial and error in rebending the rails and performing trial runs to get acceptably folded cartons. Thus, in addition to the excessive down time such a process requires, hundreds of finished cartons are often wasted too.
Carton scuffing, discoloration lines and scratches are additional problems often associated with conventional carton folding apparatus. Cartons today are often made from a combination of plastic and cardboard applied in layers to form a laminate, e.g., outside film laminate (OFL) or inside film laminate (IFL). The outside surfaces of the laminates are often damaged by the stainless steel folding rails of conventional cart on folding apparatus which acts like sandpaper and abrades the cartons.
Another problem plaguing conventional carton folding operations is the excessive down time currently required to replace teflon rails. Teflon rails must be replaced when worn or when glue builds-up on the rails. Conventional teflon rails are made entirely of costly virgin teflon and are arranged so that a set of rails are bolted together by drilling holes through each of the rails in the set at various locations in order to insert bolts through the holes to thus, connect the rails together in series. Replacement of teflon rails so bolted together is costly and time consuming because of the need to disassemble the whole assembly and to drill holes in the new rails to be placed in the teflon rail arrangements.
Current industrial carton folding operations are also experiencing difficulties with respect to excessive glue consumption. Hot glues of high viscosity are typically used and are very expensive. Folding rails shapes, line speed and glue open time are all parameters affecting the amount of glue consumed. Thus, methods and apparatus which function more efficiently to fold and compress cartons would reduce glue consumption and save money.
A need exists, therefore, for improved methods and apparatus for folding cartons using folding rails having a curvilinear surface of a predetermined curvature to consistently produce squared cartons, which are adjustable and interchangeable to reduce excessive down time by allowing for quick and easy changeover to different rail sizes for folding cartons of varying sizes, widths and flaps, i.e. full-size versus shied or to replace deformed rails, which are durable, of low maintenance and of simple installation and which use teflon rail arrangements designed to be quickly and easily replaced in order to decrease the down time and expense associated with conventional teflon rails.